The present invention relates to a seismometer. It is known that seismometers measure ground shocks having either natural causes, such as earthquakes, or unnatural causes such as explosions. A modern seismometer comprises a ground displacement sensor which usually uses the inertia of a pendulum, a transducer which transforms into an electromotive force the displacement or displacement speed of the pendulum and an electronic amplifier which amplifies the electromotive force.
There are numerous French and foreign seismometer designs which can be subdivided into two main categories.
The first type has a higher performance level with regards to the sensitivity, with a natural frequency close to 1 Hz. They are generally calibratable and can be remotely tested. However, their mechanical design does not make it possible for them to measure high acceleration of approximately 0.2 g at 0.5 Hz. Such accelerations cause excessive relative coilmagnet displacements in such equipment.
Other less sensitive seismometers have a natural frequency generally equal to or above 1 Hz, and are able to measure significant displacements. In general, they have no calibration coil and there is no possibility of finely adjusting the natural frequency. Normally, they are not equipped with internal electronics.